View Compilation Error

0_0_20798809_28854.cpp:1:1: error: 'include' does not name a type
 include <stdio.h>
 ^
0_0_20798809_28854.cpp: In function 'int main()':
0_0_20798809_28854.cpp:17:22: error: 'scanf' was not declared in this scope
         scanf("%d",&n);
                      ^
0_0_20798809_28854.cpp:21:38: error: 'memset' was not declared in this scope
         memset(a,0,500000*sizeof(int));
                                      ^
0_0_20798809_28854.cpp:38:27: error: 'printf' was not declared in this scope
         printf("%d\n",minn);
                           ^